[CursedRacing]

I don't think that you buy a full sized truck for the gas mileage anyway. But mods to increase horses power do improve gas mileage for the simple reason that your engine is becoming more efficient then it was from the factory. I think you're best bet and gain in MPG would be to get a programmer and tune it, most manufacturers set their fuel maps to run the engine rich, to reduce the chance of knock, and to keep the engine running at a cooler temperature. They can not achieve a perfect tune for every single engine they produce because of the variances during production of the engine components themselves. You can however achieve a good fuel saving tune with the help of a performance shop on your truck.

Christopher